The present invention relates to porphyrin-based materials and more particularly to nickel-porphyrin materials that exhibit fast switching times and long data-retention times.
Porphyrins are a cyclic tetrapyrrolic system consisting of a 20-carbon skeleton and have been used in a variety of electrical, optical, structural, and catalytic applications. Metal ions can covalently bond within the porphyrin structure. Various peripheral groups, both inorganic and organic, are attached to the 20-carbon skeleton to provide desired physical, chemical, and optical characteristics.
Bhardwaj et al., in U.S. Pat. No. 5,252,698 issued on Oct. 12, 1993, and U.S. Pat. No. 5,312,896 issued on May 17, 1994, describe metal-ion porphyrin-containing poly(imide). The taught polymers are useful as electrical conductors and as liquid crystal polymers.
Skalkos et al., in U.S. Pat. No. 5,424,305 issued on Jun. 13, 1995, describe purified imines of porphyrins for use in retarding growth of cancer tumors.
Morgan et al, in U.S. Pat. No. 5,438,051, disclose a family of porphyrin derivatives and metal complexes thereof having bivalent aliphatic hydrocarbon radical groups attached that are useful in detecting or treating tumors in humans or animals.
Nikies, in U.S. Pat. No. 5,011,756, issued on Apr. 30, 1991, describe a method of writing and reading optical information by using a photochiroptical effect which allows light to distinguish between two optical conformers. Circular polarized light is used to selectively photolyze one of two optical conformers to write or read information.
Liu et al., in U.S. Pat. No. 5,424,974, issued on Jun. 13, 1995, describe the use of porphyrins in writing and reading optical information using a radiation pulse and controlling the charge across the porphyrin film. An important part of the taught invention is that no structural transition is involved.
Drain et al. (Drain, C., Gentemann, S., Roberts, J., Nelson, N., Medforth, C., Jia, S., Simpson, M., Smith, K., Fajer, J., Shelnutt, J., and Holten, D., J. Am. Chem. Soc., in press) describe nickel porphyrin materials, predicted by molecular modeling calculations and subsequently synthesized, that have two stable conformational isomers with lifetimes that can be useful in optical memory applications. Drain et al. show that temperature and the matrix in which the porphyrin is placed affect the lifetime of the conformations.
Useful would be a material, such as a nickel porphyrin, that can be used in optical memory applications by controllably switching the material from one energy state to another.